// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This class works with command lines: building and parsing.
// Arguments with prefixes ('--', '-', and on Windows, '/') are switches.
// Switches will precede all other arguments without switch prefixes.
// Switches can optionally have values, delimited by '=', e.g., "-switch=value".
// An argument of "--" will terminate switch parsing during initialization,
// interpreting subsequent tokens as non-switch arguments, regardless of prefix.

// There is a singleton read-only CommandLine that represents the command line
// that the current process was started with.  It must be initialized in main().

#ifndef BASE_COMMAND_LINE_H_
#define BASE_COMMAND_LINE_H_

#include <map>
#include <stddef.h>
#include <string>
#include <vector>

#include "base/base_export.h"
#include "base/strings/string16.h"
#include "base/strings/string_piece.h"
#include "build/build_config.h"

namespace base {

class FilePath;

class BASE_EXPORT CommandLine {
public:
#if defined(OS_WIN)
    // The native command line string type.
    using StringType = string16;
#elif defined(OS_POSIX)
    using StringType = std::string;
#endif

    using CharType = StringType::value_type;
    using StringVector = std::vector<StringType>;
    using SwitchMap = std::map<std::string, StringType>;
    using StringPieceSwitchMap = std::map<StringPiece, const StringType*>;

    // A constructor for CommandLines that only carry switches and arguments.
    enum NoProgram { NO_PROGRAM };
    explicit CommandLine(NoProgram no_program);

    // Construct a new command line with |program| as argv[0].
    explicit CommandLine(const FilePath& program);

    // Construct a new command line from an argument list.
    CommandLine(int argc, const CharType* const* argv);
    explicit CommandLine(const StringVector& argv);

    // Override copy and assign to ensure |switches_by_stringpiece_| is valid.
    CommandLine(const CommandLine& other);
    CommandLine& operator=(const CommandLine& other);

    ~CommandLine();

#if defined(OS_WIN)
    // By default this class will treat command-line arguments beginning with
    // slashes as switches on Windows, but not other platforms.
    //
    // If this behavior is inappropriate for your application, you can call this
    // function BEFORE initializing the current process' global command line
    // object and the behavior will be the same as Posix systems (only hyphens
    // begin switches, everything else will be an arg).
    static void set_slash_is_not_a_switch();

    // Normally when the CommandLine singleton is initialized it gets the command
    // line via the GetCommandLineW API and then uses the shell32 API
    // CommandLineToArgvW to parse the command line and convert it back to
    // argc and argv. Tests who don't want this dependency on shell32 and need
    // to honor the arguments passed in should use this function.
    static void InitUsingArgvForTesting(int argc, const char* const* argv);
#endif

    // Initialize the current process CommandLine singleton. On Windows, ignores
    // its arguments (we instead parse GetCommandLineW() directly) because we
    // don't trust the CRT's parsing of the command line, but it still must be
    // called to set up the command line. Returns false if initialization has
    // already occurred, and true otherwise. Only the caller receiving a 'true'
    // return value should take responsibility for calling Reset.
    static bool Init(int argc, const char* const* argv);

    // Destroys the current process CommandLine singleton. This is necessary if
    // you want to reset the base library to its initial state (for example, in an
    // outer library that needs to be able to terminate, and be re-initialized).
    // If Init is called only once, as in main(), Reset() is not necessary.
    // Do not call this in tests. Use base::test::ScopedCommandLine instead.
    static void Reset();

    // Get the singleton CommandLine representing the current process's
    // command line. Note: returned value is mutable, but not thread safe;
    // only mutate if you know what you're doing!
    static CommandLine* ForCurrentProcess();

    // Returns true if the CommandLine has been initialized for the given process.
    static bool InitializedForCurrentProcess();

#if defined(OS_WIN)
    static CommandLine FromString(const string16& command_line);
#endif

    // Initialize from an argv vector.
    void InitFromArgv(int argc, const CharType* const* argv);
    void InitFromArgv(const StringVector& argv);

    // Constructs and returns the represented command line string.
    // CAUTION! This should be avoided on POSIX because quoting behavior is
    // unclear.
    StringType GetCommandLineString() const
    {
        return GetCommandLineStringInternal(false);
    }

#if defined(OS_WIN)
    // Constructs and returns the represented command line string. Assumes the
    // command line contains placeholders (eg, %1) and quotes any program or
    // argument with a '%' in it. This should be avoided unless the placeholder is
    // required by an external interface (eg, the Windows registry), because it is
    // not generally safe to replace it with an arbitrary string. If possible,
    // placeholders should be replaced *before* converting the command line to a
    // string.
    StringType GetCommandLineStringWithPlaceholders() const
    {
        return GetCommandLineStringInternal(true);
    }
#endif

    // Constructs and returns the represented arguments string.
    // CAUTION! This should be avoided on POSIX because quoting behavior is
    // unclear.
    StringType GetArgumentsString() const
    {
        return GetArgumentsStringInternal(false);
    }

#if defined(OS_WIN)
    // Constructs and returns the represented arguments string. Assumes the
    // command line contains placeholders (eg, %1) and quotes any argument with a
    // '%' in it. This should be avoided unless the placeholder is required by an
    // external interface (eg, the Windows registry), because it is not generally
    // safe to replace it with an arbitrary string. If possible, placeholders
    // should be replaced *before* converting the arguments to a string.
    StringType GetArgumentsStringWithPlaceholders() const
    {
        return GetArgumentsStringInternal(true);
    }
#endif

    // Returns the original command line string as a vector of strings.
    const StringVector& argv() const { return argv_; }

    // Get and Set the program part of the command line string (the first item).
    FilePath GetProgram() const;
    void SetProgram(const FilePath& program);

    // Returns true if this command line contains the given switch.
    // Switch names must be lowercase.
    // The second override provides an optimized version to avoid inlining codegen
    // at every callsite to find the length of the constant and construct a
    // StringPiece.
    bool HasSwitch(const StringPiece& switch_string) const;
    bool HasSwitch(const char switch_constant[]) const;

    // Returns the value associated with the given switch. If the switch has no
    // value or isn't present, this method returns the empty string.
    // Switch names must be lowercase.
    std::string GetSwitchValueASCII(const StringPiece& switch_string) const;
    FilePath GetSwitchValuePath(const StringPiece& switch_string) const;
    StringType GetSwitchValueNative(const StringPiece& switch_string) const;

    // Get a copy of all switches, along with their values.
    const SwitchMap& GetSwitches() const { return switches_; }

    // Append a switch [with optional value] to the command line.
    // Note: Switches will precede arguments regardless of appending order.
    void AppendSwitch(const std::string& switch_string);
    void AppendSwitchPath(const std::string& switch_string,
        const FilePath& path);
    void AppendSwitchNative(const std::string& switch_string,
        const StringType& value);
    void AppendSwitchASCII(const std::string& switch_string,
        const std::string& value);

    // Copy a set of switches (and any values) from another command line.
    // Commonly used when launching a subprocess.
    void CopySwitchesFrom(const CommandLine& source,
        const char* const switches[],
        size_t count);

    // Get the remaining arguments to the command.
    StringVector GetArgs() const;

    // Append an argument to the command line. Note that the argument is quoted
    // properly such that it is interpreted as one argument to the target command.
    // AppendArg is primarily for ASCII; non-ASCII input is interpreted as UTF-8.
    // Note: Switches will precede arguments regardless of appending order.
    void AppendArg(const std::string& value);
    void AppendArgPath(const FilePath& value);
    void AppendArgNative(const StringType& value);

    // Append the switches and arguments from another command line to this one.
    // If |include_program| is true, include |other|'s program as well.
    void AppendArguments(const CommandLine& other, bool include_program);

    // Insert a command before the current command.
    // Common for debuggers, like "valgrind" or "gdb --args".
    void PrependWrapper(const StringType& wrapper);

#if defined(OS_WIN)
    // Initialize by parsing the given command line string.
    // The program name is assumed to be the first item in the string.
    void ParseFromString(const string16& command_line);
#endif

private:
    // Disallow default constructor; a program name must be explicitly specified.
    CommandLine();
    // Allow the copy constructor. A common pattern is to copy of the current
    // process's command line and then add some flags to it. For example:
    //   CommandLine cl(*CommandLine::ForCurrentProcess());
    //   cl.AppendSwitch(...);

    // Internal version of GetCommandLineString. If |quote_placeholders| is true,
    // also quotes parts with '%' in them.
    StringType GetCommandLineStringInternal(bool quote_placeholders) const;

    // Internal version of GetArgumentsString. If |quote_placeholders| is true,
    // also quotes parts with '%' in them.
    StringType GetArgumentsStringInternal(bool quote_placeholders) const;

    // Reconstruct |switches_by_stringpiece| to be a mirror of |switches|.
    // |switches_by_stringpiece| only contains pointers to objects owned by
    // |switches|.
    void ResetStringPieces();

    // The singleton CommandLine representing the current process's command line.
    static CommandLine* current_process_commandline_;

    // The argv array: { program, [(--|-|/)switch[=value]]*, [--], [argument]* }
    StringVector argv_;

    // Parsed-out switch keys and values.
    SwitchMap switches_;

    // A mirror of |switches_| with only references to the actual strings.
    // The StringPiece internally holds a pointer to a key in |switches_| while
    // the mapped_type points to a value in |switches_|.
    // Used for allocation-free lookups.
    StringPieceSwitchMap switches_by_stringpiece_;

    // The index after the program and switches, any arguments start here.
    size_t begin_args_;
};

} // namespace base

#endif // BASE_COMMAND_LINE_H_
